In general, in a rotating anode X-ray tube, an eccentrically arranged cathode and an anode target having a nearly umbrella shape are arranged in opposition to each other in a vacuum envelope in which a vacuum-tight atmosphere is held. The anode target is supported on a rotating mechanism, and is made rotatable. Outside the vacuum envelope, a stator is arranged to correspond to the rotating mechanism, and drives the rotating mechanism.
In a conventional rotating anode X-ray tube, the anode fixing body is formed of a material (containing a ferroalloy) having poor thermal conductivity, and hence there is a possibility of the temperature of the ball bearings, particularly, the temperature of the ball bearing closer to the anode target being raised high.
In the conventional rotating anode X-ray tube, the anode fixing body is normally formed of Fe, a ferroalloy or the like which is a magnetic substance material. The anode fixing body formed of a magnetic substance is opposed to a magnetic core of the stator coil with a rotor (rotating cylinder) held between them, thereby constituting a magnetic circuit. By virtue of the existence of the magnetic circuit, the density of the magnetic flux passing through the rotating cylinder is enhanced, and it is possible to rotate the rotating cylinder with a high degree of efficiency. Further, the rotating anode X-ray tube is normally provided with a high-radiation film configured to diffuse heat by radiation on the outer circumferential surface of the rotating cylinder.